Cortical Excitability in Cyclic Vomiting Syndrome

This exploratory study will determine if there are differences in cortical excitability between patients suffering from cyclic vomiting syndrome (CVS) and healthy control subjects, as assessed by a non-invasive method of brain stimulation (Transcranial Magnetic Stimulation, TMS).

This exploratory study will determine if there are differences in cortical excitability between patients suffering from cyclic vomiting syndrome (CVS) and healthy control subjects, as assessed by a non-invasive method of brain stimulation (Transcranial Magnetic Stimulation, TMS). Using the paired-pulse TMS paradigm, intracortical inhibition and facilitation of cortical circuitry will be assessed by stimulating the motor cortex and using the electromyographic (EMG) response of a target muscle as readout. In such studies, a conditioning stimulus modulates the amplitude of the motor-evoked potential (MEP) produced by the test stimulus. Depending on the inter-stimulus interval, effects can be attributed to different aspects of cortical processing. Brief intervals (1-5 ms) will be used to assess short-interval intracortical inhibition (SICI) and short-interval intracortical facilitation (SICF), intermediate intervals (7-20 ms) to assess intracortical facilitation (ICF) and long intervals (50-200 ms) to assess long-interval intracortical inhibition (LICI). Some clinical, demographic, and autonomic data (i.e. EKG) will be recorded and used as covariates to investigate any systematic impact on cortical excitability measures collected with the paired-pulse protocols.

This is a comparative study looking at differences in electrophysiologic measures of cortical excitability between those with Cyclic Vomiting Syndrome and healthy controls.

Using the paired-pulse TMS paradigm, intracortical inhibition and facilitation of cortical circuitry will be assessed by stimulating the motor cortex and using the electromyographic (EMG) response of a target muscle as readout. In such studies, a conditioning stimulus modulates the amplitude of the motor-evoked potential (MEP) produced by the test stimulus. Depending on the inter-stimulus interval, effects can be attributed to different aspects of cortical processing. Brief intervals (1-5 ms) will be used to assess short-interval intracortical inhibition (SICI) and short-interval intracortical facilitation (SICF), intermediate intervals (7-20 ms) to assess intracortical facilitation (ICF) and long intervals (50-200 ms) to assess long-interval intracortical inhibition (LICI).

Autonomic function will be determined using continuously recorded EKG and used as covariates to investigate any systematic impact on cortical excitability measures collected with the paired-pulse protocols.

Percentage Change in Paired Pulse (PP) TMS induced MEP responses with inhibitory or facilitatory stimulation.

Inclusion Criteria: diagnosis of CVS Exclusion Criteria: history of CVS (for healthy control population only) psychosis or altered cognitive status history of head injury, metal in the skull, stroke, or a history of seizures implantable devices, such as a pacemaker or nerve stimulator current use of the following medications or use of substances which are known to lower the seizure threshold: clozapine (Clozaril), chlorpromazine (Thorazine), amphetamines or methamphetamine, Ecstasy, Ketamine, Angel Dust/PCP, cocaine, or 3 or more alcoholic drinks per day pregnancy

There is no current plan to place participant data into a open-access, shared data repository. However, a data sharing agreement can be made if requested.